CHEYENNE, Wyo. (AP) -- Tests have confirmed finding the bacterial disease brucellosis in a single cattle herd in northern Wyoming, but so far there is no indication that the disease has spread to surrounding herds in Park County, state Veterinarian Jim Logan said.

"Everything else we have results on so far has been negative," Logan said Wednesday.

Logan said he doesn't expect the state will lose its brucellosis-free status at this time. Losing the status would mean restrictions and expensive testing for Wyoming's cattle industry to keep the disease from spreading.

Brucellosis can cause spontaneous abortions, infertility, decreased milk production and weight loss in cattle, elk, bison and other mammals. It persists in herds of wild elk and bison around Yellowstone National Park and has periodically passed to cattle in Montana, Idaho and Wyoming.

Wyoming last had a confirmed case of brucellosis in a cattle herd just over two years ago in Sublette County.

A dozen herds altogether have been quarantined in Park County since Oct. 26 after initial testing indicated brucellosis in several cows, Logan said.

So far, about 1,800 cattle have been tested with another 1,700 head scheduled to be tested. Officials expect to be done testing by next Monday.

Logan said he believes the last case of livestock brucellosis in Park County occurred in the late 1970s or early 1980s. Park County borders Montana, but Logan said he's not aware of any cattle from Montana intermingling with the quarantined Wyoming herds.

While four cows from the herd with the disease have been slaughtered, the rest of the herd will remain under quarantine for about a year, he said.

"They'll have to go through a series of testing before the quarantine can be released," Logan said. "As long as we don't find additional animals on subsequent tests, certainly the hope is that we'll be able to test him out and there wouldn't have to be a depopulation or anything, just a series of tests."

The surrounding herds will be released from quarantine sooner as long as no more cases are found, he said.